The at least one fully protected and/or the at least one fully unprotected calix[4]resorcinarene can have a calixarene structure selected from the group consisting of C-tetramethyl-calix[4]resorcinarene, C-tetraphenyl-calix[4]resorcinarene, and C-isopropylphenyl-calix[4]resorcinarene.
As the minimum critical dimension continues to shrink to less than 50 nanometers (nm), it is becoming increasingly difficult to simultaneously meet critical performance criteria, sensitivity, resolution, and line edge roughness (LER). The size of polymers typically employed in chemical amplification photoresists is beginning to influence performance at these dimensions. For example, it is believed that the magnitude of line edge roughness is directly correlated to the molecular weight of the base polymer in the photoresist. As a result, a number of photoresists based on low molecular weight polymers or non-polymers have been proposed to address the performance issues needed for these advanced design rules.
Calixarenes are non-polymeric phenolic macrocylic compounds that have recently attracted a great deal of attention. Calixarenes were discovered and methods of synthesis devised in the 1950's. Initial work with these compounds focused on potential biological applications, particularly in constructing systems for mimicking the catalytic activity of certain enzymes. Other work has suggested utility as synthetic analogues of cyclodextrins, and in extraction and separation processes. With regard to the use of calixarenes in device manufacture, calixarenes that have been partially protected with acid labile groups have been extensively evaluated as molecular glass resists and dissolution inhibitors. In these molecular glass applications, the partially protected calix[4]resorcinarenes were claimed to be structurally monomodal whereas, in actuality, partial protection of ccc and ctt isomer mixtures resulted in highly multimodal distributions of the isomeric structures. However, truly monomodal 100% protected pure isomers have been employed as dissolution inhibitors.
While lithographic results from the use of partially protected calixarenes in positive tone resists has shown some promise, increased performance robustness is needed.